Hello MRA community! First time posting and have a couple questions. We are going to purchase and install an Airsal 70 cc cylinder kit onto our 2005 Streetmate. We have already installed a biturbo exhaust. Previous owner had varnishing problems and partially resolved by cleaning and new jets but the bike has always experienced erratic performance with the existing Dellorto PHVA 14mm carb. So, we intend to order the Dellorto PHVA 17.5mm carb as part of the upgrade. I realize tuning and jetting will be somewhat of a trial and error process, so would it be wise to order several main jets and idle jets? Are there any tricks or techniques to drilling out jets to gain bigger size. Since 14mm to 17.5mm is a big jump, should I expect some bogging at low rpm? Thanks in advance.

I'd strongly recommend not trying to drill out jets. They're not that expensive, and the risk just isn't worth it. You're putting some serious money into your bike, so make sure you tune it to get the most performance and life. Buy a handful of jet sizes and go through the process.

Also, be sure that you perform "plug chops" properly as you go. See Fred's Guide in the Moped Repair section if you don't know how.

If you do it right, the engine should not be unreasonably stressed by the upgrade. The clutches, however, are another matter. Expect about 3,000 miles out of them on a kitted bike. Fortunately, they're easy to change.

...Operating with impunity in the legal gray area between bicycles and motorcycles....